Variable valve lift apparatus

ABSTRACT

A variable valve lift apparatus includes a camshaft with a first cam lobe and a second cam lobe, a cam follower with a first follower contacting the first cam lobe and a second follower contacting the second cam lobe, a connection rotatably connecting the first follower to the second follower, a main body supporting the first follower and the second follower, a connector selectively connecting the first follower and the second follower to the main body, a lost motion elastic member provided on the main body for supplying restoring force to the first follower and the second follower, and a valve configured to be opened and closed by the cam follower.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to, and the benefit of, Korean PatentApplication No. 10-2007-0131573, filed in the Korean IntellectualProperty Office on Dec. 14, 2007, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a variable valve lift apparatus with alow lift mode, a high lift mode, and a CDA mode.

(b) Description of the Related Art

A typical combustion chamber of an automotive engine is provided with anintake valve, for supplying an air/fuel mixture, and an exhaust valve,for expelling burned gas. The intake and exhaust valves are opened andclosed by a valve lift apparatus connected to a crankshaft.

A conventional valve lift apparatus has a fixed valve lift amount due toa fixed cam shape. Therefore, it is impossible to adjust the amount ofgas that is introduced or exhausted. However, valve timing and amount oflift should ideally be optimized for different driving speeds.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

A variable valve lift apparatus includes a camshaft with a first camlobe and a second cam lobe, a cam follower with a first followercontacting the first cam lobe and a second follower contacting thesecond cam lobe, a connection rotatably connecting the first follower tothe second follower, a main body supporting the first follower and thesecond follower, a connector selectively connecting the first followerand the second follower to the main body, a lost motion elastic memberprovided on the main body for supplying restoring force to the firstfollower and the second follower, and a valve configured to be openedand closed by the cam follower.

The connector may include several locker pins. The apparatus may furtherinclude a hydraulic pressure supplying apparatus that selectivelysupplies hydraulic pressure to the locker pins for the first follower orthe second follower to be connected to the main body. The locker pinsmay include a first locker pin, a second locker pin, and a return pinthat supplies a restoring force to the first locker pin. The hydraulicpressure supplying apparatus may include a first hydraulic pressuresupplying apparatus that supplies hydraulic pressure to the first lockerpin, and a second hydraulic pressure supplying apparatus that supplieshydraulic pressure to the second locker pin. Each hydraulic pressuresupplying apparatus may include a hydraulic piston and a blocking plate.

When the first locker pin is supplied hydraulic pressure from the firsthydraulic pressure supplying apparatus, it may disconnect the firstfollower from the main body. When the second locker pin is suppliedhydraulic pressure from the second hydraulic pressure supplyingapparatus, it may connect the second follower to the main body.

The apparatus may further include a first supporting pin on the mainbody, a first supporting pin hole in the return pin for preventinginterference with the supporting pin, and a first return spring betweenthe supporting pin and the return pin for supplying restoring force tothe return pin.

The apparatus may further include a second supporting pin in the secondfollower, a second supporting pin hole in the second locker pin forpreventing interference with the second supporting pin, and a secondreturn spring disposed between the second supporting pin and the secondlocker pin for supplying restoring force to the second locker pin.

The apparatus may further include a stopper between the secondsupporting pin and the second locker pin.

The cam follower may include a first roller contacting the first camlobe and a second roller contacting the second cam lobe. The firstfollower may include a supporting step for preventing the first followerfrom disconnecting from the main body.

The lost motion elastic member may include a spring cap, a plunger, anda lost motion spring between the spring cap and the plunger.

The connection may include a connecting pin and a connecting pininsertion hole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a variable valve lift apparatusaccording to an exemplary embodiment.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.

FIG. 3 is a partial exploded perspective view of the apparatus of FIG.1.

FIG, 4 is an exploded perspective view of a connector of the apparatusof FIG. 1.

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 1.

FIG. 6 is a perspective view of a connector of the apparatus of FIG. 1in a low lift mode.

FIG. 7 is a perspective view of the connector of FIG. 6 in a high liftmode.

FIG. 8 is a view of the connector of FIG. 6 in a CDA lift mode.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An exemplary embodiment of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

Referring to FIG. 1 to FIG. 5, a variable valve lift apparatus accordingto an exemplary embodiment of the present invention includes a camshaft100 including a first cam lobe 110 and a second cam lobe 120.

Referring to FIG. 2, a cam follower 200 includes a first follower 210and a second follower 220. The first follower 210 contacts the first camlobe 110 and the second follower 220 contacts the second cam lobe 120.

A first roller 215 contacting the first cam lobe 110 is disposed on thefirst follower 210, and a second roller 225 contacting the second camlobe 120 is disposed on the second follower 220.

The followers 210, 220 are rotatably connected by a connection 230,which includes a connecting pin insertion hole 250 and a connecting pin240 disposed within the connecting pin insertion hole 250.

The first follower 210 and the second follower 220 are supported by amain body 300.

A connector 400 selectively connects the followers 210, 220 to the mainbody 300.

A lost motion elastic member 500 (FIG. 5) is disposed in the main body300 for supplying restoring force to the first follower 210 and thesecond follower 220.

A valve 700 is selectively opened and closed by the cam follower 200.

The connector 400 includes a first locker pin 410, a second locker pin430, and a return pin 420 that supplies restoring force to the firstlocker pin 410.

A hydraulic pressure supplying apparatus supplies hydraulic pressure tothe locker pins 410, 430 so that the first follower 210 or the secondfollower 220 may be selectively connected with the main body 300.

The hydraulic pressure supplying apparatus includes a first hydraulicpressure supplying apparatus 610 supplying hydraulic pressure to thefirst locker pin 410, and a second hydraulic pressure supplyingapparatus 650 supplying hydraulic pressure to the second locker pin 430.

The first hydraulic pressure supplying apparatus 610 includes a firsthydraulic piston 620 and a first blocking plate 630, and the secondhydraulic pressure supplying apparatus 650 includes a second hydraulicpiston 660 and a second blocking plate 670.

The first locker pin 410 selectively receives hydraulic pressure fromthe first hydraulic pressure supplying apparatus 610 for disconnectingthe first follower 210 from the main body 300. That is, when hydraulicpressure is not supplied to the first locker pin 410, it is disposed inboth the first follower 210 and the main body 300, connecting the firstfollower 210 and the main body 300 (see FIGS. 2 and 7). When hydraulicpressure is supplied to the first locker pin 410, it is disposed in onlythe first follower 210, disconnecting it from the main body 300 (seeFIG. 8).

The second locker pin 430 selectively receives hydraulic pressure fromthe second hydraulic pressure supplying apparatus 650 for connecting thesecond follower 220 to the main body 300. That is, when hydraulicpressure is not supplied to the second locker pin 430, it is disposed inonly the second follower 220, disconnecting it from the main body 300(see FIGS. 2 and 8). When hydraulic pressure is supplied to the secondlocker pin 430, it is disposed in both the second follower 220 and themain body 300, connecting the second follower 220 and the main body 300(see FIG. 7).

Referring to FIG. 2, a first supporting pin 422 is provided at the mainbody 300, and a first return spring 424 is disposed between the firstsupporting pin 422 and the return pin 420 and supplies restoring forceto the return pin 420.

A first supporting pin hole 426 is formed in the return pin 420 toprevent interference of the return pin 420 and the first supporting pin422 when the return pin 420 moves.

A second supporting pin 432 is inserted into the second follower 220,and a second supporting pin hole 436 is formed to the second locker pin430 for preventing interference of the second supporting pin 432.

A second return spring 434 is disposed between the second supporting pin432 and the second locker pin 430 for supplying restoring force to thesecond locker pin 430.

A stopper 438 is disposed between the second supporting pin 432 and thelocker pin 430 for preventing the second supporting pin 432 from movingmore than a certain distance.

As shown in FIG. 3, a supporting step 260 is provided on the firstfollower 210 for preventing the first follower 210 from separating fromthe main body 300.

Referring to FIG. 5, the lost motion elastic member 500 includes aspring cap 510, a plunger 520, and a lost motion spring 530 disposedbetween the spring cap 510 and the plunger 520.

Referring to FIG. 2 and FIG. 5, when the first locker pin 410 connectsthe main body 300 with the first follower 210, the first cam lobe 110pushes the first roller 215 and then the follower 210 pivotally rotateswith respect to the first locker pin 410, and opens and closes the valve700.

When the first locker pin 410 is inserted within the first follower 210,a lost motion of the follower 2 10 occurs and the valve 700 is notopened or closed even if the first cam lobe 10 pushes the first roller215.

An operation of the second follower 220 is similar to that of the firstfollower 210 so a detailed explanation thereof will be omitted.

Now, for ease of description, the first cam lobe 110 will be considereda low lift cam lobe, and the second cam lobe 120 will be considered ahigh lift cam lobe.

Referring to FIG. 2 and FIG. 6, a low lift mode of the variable valvelift apparatus according to an exemplary embodiment of the presentinvention will be explained.

In the low lift mode, hydraulic pressure is not supplied. As shown inFIG. 6, the second locker pin 430 is disposed within the second follower220, and the first locker pin 410 connects the main body 300 with thefirst follower 210.

Even if the second cam lobe 120 rotates, the second follower 220 haslost motion and the valve 700 is opened and closed by the rotation ofthe first cam 110 lobe through the first follower 210.

Referring to FIG. 2 and FIG. 7, a high lift mode of the variable valvelift apparatus according to an exemplary embodiment of the presentinvention will be explained.

In the high lift mode, hydraulic pressure is supplied to the secondlocker pin 430 through the second hydraulic pressure supplying apparatus650.

As shown in FIG. 7, the second locker pin 430 connects the secondfollower 220 with the main body 300, and the first locker pin 410connects the main body 300 with the first follower 210.

Rotation of both the first cam lobe 110 and the second cam lobe 120 aretransmitted to the first follower 210 and the second follower 220,respectively, but the valve 700 is opened by the second cam lobe 220 asa high lift cam lobe.

Referring to FIG. 2 and FIG. 8, a CDA mode of the variable valve liftapparatus according to an exemplary embodiment of the present inventionwill be explained.

In the CDA mode, hydraulic pressure is supplied to the first locker pin410 through the first hydraulic pressure supplying apparatus 610.

As shown in FIG. 8, the first locker pin 410 and the second locker pin430 are disposed within the first follower 210 and the second follower220, respectively, so that the first follower 210 and the secondfollower 220 are disconnected from the main body 300.

Thus, both the first follower 210 and the second follower 220 have lostmotion so that the valve 700 is not opened and closed.

The operation of the first hydraulic pressure supplying apparatus 610and the second hydraulic pressure supplying apparatus 650 may becontrolled by an engine control unit (ECU, not shown), which determinesoperation conditions of the engine through sensors, and controls thesupply of hydraulic pressure. The ECU may include a processor, memory,and associated hardware, software, and/or firmware as may be selectedand programmed by a person of ordinary skill in the art based on theteachings herein.

In the drawings and the description, the first cam lobe 110 and thesecond cam lobe 120 are considered to be a low lift cam lobe and a highlift cam lobe, respectively, but the opposite may be true, by a simplemodification of the conjunction part 400 in a manner that will beapparent to those of ordinary skill in the art.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A variable valve lift apparatus comprising: a camshaft comprising afirst cam lobe and a second cam lobe; a cam follower comprising a firstfollower contacting the first cam lobe and a second follower contactingthe second cam lobe; a connection rotatably connecting the firstfollower to the second follower; a main body supporting the firstfollower and the second follower; a connector selectively connecting thefirst follower and the second follower to the main body; a lost motionelastic member provided on the main body for supplying restoring forceto the first follower and the second follower; and a valve configured tobe opened and closed by the cam follower.
 2. The variable valve liftapparatus of claim 1, wherein the connector comprises a plurality oflocker pins.
 3. The variable valve lift apparatus of claim 2, furthercomprising a hydraulic pressure supplying apparatus that selectivelysupplies hydraulic pressure to the plurality of locker pins for thefirst follower or the second follower to be connected to the main body.4. The variable valve lift apparatus of claim 3, wherein the pluralityof locker pins comprise a first locker pin, a second locker pin, and areturn pin that supplies a restoring force to the first locker pin. 5.The variable valve lift apparatus of claim 4, wherein the hydraulicpressure supplying apparatus comprises a first hydraulic pressuresupplying apparatus that supplies hydraulic pressure to the first lockerpin, and a second hydraulic pressure supplying apparatus that supplieshydraulic pressure to the second locker pin.
 6. The variable valve liftapparatus of claim 5, wherein the first hydraulic pressure supplyingapparatus comprises a hydraulic piston and a blocking plate.
 7. Thevariable valve lift apparatus of claim 5, wherein the second hydraulicpressure supplying apparatus comprises a hydraulic piston and a blockingplate.
 8. The variable valve lift apparatus of claim 5, wherein when thefirst locker pin is supplied hydraulic pressure from the first hydraulicpressure supplying apparatus, the first locker pin disconnects the firstfollower from the main body.
 9. The variable valve lift apparatus ofclaim 5, wherein when the second locker pin is supplied hydraulicpressure from the second hydraulic pressure supplying apparatus, thesecond locker pin connects the second follower to the main body.
 10. Thevariable valve lift apparatus of claim 4, further comprising: asupporting pin provided on the main body; a supporting pin hole in thereturn pin for preventing interference with the supporting pin; and areturn spring disposed between the supporting pin and the return pin forsupplying restoring force to the return pin,
 11. The variable valve liftapparatus of claim 4, further comprising: a supporting pin in the secondfollower; a supporting pin hole in the second locker pin for preventinginterference with the supporting pin; and a return spring disposedbetween the supporting pin and the second locker pin for supplyingrestoring force to the second locker pin.
 12. The variable valve liftapparatus of claim 11, further comprising a stopper disposed between thesupporting pin and the second locker pin.
 13. The variable valve liftapparatus of claim 1, wherein the cam follower comprises a first rollercontacting the first cam lobe and a second roller contacting the secondcam lobe.
 14. The variable valve lift apparatus of claim 13, wherein thefirst follower comprises a supporting step for preventing the firstfollower from disconnecting from the main body.
 15. The variable valvelift apparatus of claim 1, wherein the lost motion elastic membercomprises a spring cap, a plunger, and a lost motion spring disposedbetween the spring cap and the plunger.
 16. The variable valve liftapparatus of claim 1, wherein the connection comprises a connecting pinand a connecting pin insertion hole.